In a manufacturing step of a mask blank, particularly the mask blank, which is an original substrate of a transfer mask formed with a transfer pattern becoming a pattern of an electronic circuit on a substrate, after a resist film is formed on a substrate surface forming the mask blank, the substrate passes through various kinds of processing steps in which it is held by a carrying mechanism or inserted/removed into/from a substrate housing case. At this time, the peripheral edge of the substrate forming the mask blank comes into contact with a chuck part of the carrying mechanism and a housing groove of the housing case, and the resist film on the peripheral edge of the substrate is peeled to become a dust generation source. Accordingly, a problem is that the peeled resist adheres to a main surface of the mask blank, resulting in a defect.
Therefore, when manufacturing the mask blank, the substrate is subjected to processing in such a manner that by spin-coating the resist thereon to form the resist film, and thereafter the resist film on the peripheral edge of the substrate is previously removed. In the processing, a chemical liquid by which the resist is dissolved is fed to the resist on the peripheral edge of the substrate while rotating the substrate horizontally around a specified rotation center, and the resist film on the peripheral edge of the substrate is thereby dissolved and removed.
For example, a technique to remove the unnecessary resist film on the peripheral edge of the substrate includes a method disclosed in Patent Document 1.
The method of removing the unnecessary films comprising: forming the resist film by the spin-coating method, covering the surface of the substrate with a cover member formed with a plurality of fine holes on the peripheral edge of the substrate (part located in the upper part of the unnecessary film to be removed), and feeding the chemical liquid (solvent) by which the resist is dissolved from above this cover member, while the substrate and the cover member are integrally rotated. The solvent thus fed is fed to the peripheral edge of the substrate through the fine holes, and the resist formed on the peripheral edge of the substrate is thereby dissolved and removed.
(Patent Document 1)
Japanese Patent Laid Open No. 2001-259502